Network computing has grown at a phenomenal rate over the last decade. In a network computing environment, a user has access to the computing power of multiple computers located on a network. Sun Microsystems Inc., a leader in network computing has even gone as far as developing a marketing campaign around the slogan "The Network Is the Computer".TM. to emphasize the commercial success of this growing segment of the computing market. Recently, this slogan has become reality as millions of users have tapped the computing resources available from the thousands of computers on private intranets, the Internet and the World Wide Web.
Many individuals and organizations in the computer and communications industries tout the Internet as the fastest growing market on the planet. In the 1990s, the number of users of the Internet appears to be growing exponentially with no end in sight. In June of 1995, an estimated 6,642,000 hosts were connected to the Internet; this represented an increase from an estimated 4,852,000 hosts in January, 1995. The number of hosts appears to be growing at around 75% per year. Among the hosts, there were approximately 120,000 networks and over 27,000 web servers. The number of web servers appears to be approximately doubling every 53 days.
In July 1995, with over 1,000,000 active Internet users, over 12,505 usenet news groups, and over 10,000,000 usenet readers, the Internet appears to be destined to explode into a very large market for a wide variety of information and multimedia services.
In addition, to the public carrier network or Internet, many corporations and other businesses are shifting their internal information systems onto an intranet as a way of more effectively sharing information within a corporate or private network. The basic infrastructure for an intranet is an internal network connecting servers and desktops, which may or may not be connected to the Internet through a firewall. These intranets provide services to desktops via standard open network protocols which are well established in the industry. Intranets provide many benefits to the enterprises which employ them, such as simplified internal information management and improved internal communication using the browser paradigm. Integrating Internet technologies with a company's enterprise infrastructure and legacy systems also leverages existing technology investment for the party employing an intranet. As discussed above, intranets and the Internet are closely related, with intranets being used for internal and secure communications within the business and the Internet being used for external transactions between the business and the outside world. For the purposes of this document, the term "network" includes both the Internet and intranets. However, the distinction between the Internet and an intranet should be borne in mind where applicable.
In 1990, programmers at Sun Microsystems wrote a universal programming language. This language was eventually named the JAVA programming language. (JAVA is a trademark of Sun Microsystems of Mountain View, Calif.) The JAVA programming language resulted from programming efforts which initially were intended to be coded in the C++ programming language;
therefore, the JAVA programming language has many commonalities with the C++ programming language. However, the JAVA programming language is a simple, object-oriented, distributed, interpreted, yet high performance, robust, yet safe, secure, dynamic, architecture neutral, portable, and multi-threaded language.
The JAVA programming language has emerged as the programming language of choice for the Internet as many large hardware and software companies have licensed it from Sun Microsystems. The JAVA programming language and environment is designed to solve a number of problems in modem programming practice. The JAVA programming language omits many rarely used, poorly understood, and confusing features of the C++ programming language. These omitted features primarily consist of operator overloading, multiple inheritance, and extensive automatic coercions. The JAVA programming language includes automatic garbage collection that simplifies the task of programming because it is no longer necessary to allocate and free memory as in the C++ programming language. The JAVA programming language restricts the use of pointers as defined in the C++ programming language, and instead has true arrays in which array bounds are explicitly checked, thereby eliminating vulnerability to many viruses and nasty bugs. The JAVA programming language includes objective-C interfaces and specific exception handlers.
The JAVA programming language has an extensive library of routines for coping easily with TCP/IP protocol (Transmission Control Protocol based on Internet protocol), HTTP (Hypertext Transfer Protocol) and FTP (File Transfer Protocol). The JAVA programming language is intended to be used in networked/distributed environments. The JAVA programming language enabled the construction of virus-free, tamper-free systems. The authentication techniques are based on public-key encryption.
These networked/distributed applications written in "write once run everywhere" programming languages such as JAVA need peripheral devices which operate under the same paradigm. Applications executed in a networked/distributed environment should also be able to interface with a wide variety of peripheral devices in an orthogonal and simple to use fashion. For example, users should be able to execute different application programs on multiple heterogeneous platforms and then print output from these applications on a variety of printer devices without concern over: device drivers; printer capabilities; or executing preprocessing data conversion routines.
Further, networked peripheral devices should be just as available for distributed processing as networked computers. For example, if a printer is attached to an intranet or the Internet, a user should be able to print a job remotely from work or home as long as a communication signal can be established between the user's remote computing device and the printer device. Likewise, the user should be able to execute applications and access other peripheral devices such as digital image capture devices, telecommunication devices, display devices, or even a sound generation device in a similar fashion. Essentially, the user should be able to use a peripheral device based on the needs of an application and not the availability of a particular device driver. For example, a desktop publishing application should be able to take pictures from different digital cameras located all over the world. If these digital cameras are coupled to the users computer over a network, the user should be able to select the camera which has a desired image and not be limited to the cameras compatible with his or her particular hardware platform. Essentially, a remote user should have the same amount of control over the camera's operation as a user would holding the camera. The user should then be able to display this image on a screen, print the image out on a printer, or deliver the image to a host computer. The image should even be compatible with devices such as a facsimile machine or digital based television such as HDTV (high definition television).
Moreover, peripheral device manufacturers and application developers should be able to develop products which work together for several types of peripheral devices and a wide range of operating environments. The peripheral device manufacturer should provide a predetermined set of functionalities capable of accessing the various features of the particular peripheral device. These finctionalities should be robust and easy to use so that people can rely on the technology for a long period of time. On the application development side, software developers should be able to make abstract calls to certain predetermined function calls without concern for the actual peculiarities of the underlying peripheral device. For example, a single printer management application should be able to manage and configure a wide range of printers, from a number of different manufacturers using a single GUI (graphical user interface) application. This would enable a user to select the printer device best suited for the print job rather than the printer compatible with the loaded device drivers.
Unfortunately, at present users do not have the luxury of using a peripheral device on a network unless their computer has the device driver required by the specific application and peripheral device combinations because the existing systems use a device driver to convert information generated by the application into a format a peripheral device can use. Typically, the driver receives data from the application, formats the data in a manner acceptable to the peripheral device, sends the data over the appropriate communication channel, and then provides the user with status of the job. Developing device drivers is complex because the peripheral device and the particular application are typically not developed using a standard interface. The device driver must be written to conform to the hardware specifications of the peripheral device. For example, obtaining status on a printer requires that the driver must interpret low level signals sent over the hardware interface. If the hardware is modified or changes, the device driver must also be modified accordingly.
It follows that developing device drivers or upgrades to the device drivers is an expensive and challenging project for most peripheral device manufacturers. In some cases, developing the device drivers can be a more daunting task than developing the peripheral device itself. For example, the peripheral device manufacturer must develop a different device driver for each different application, hardware platform, operating system, and sometimes also for each of the different versions associated with these different categories. This takes a significant amount of research and development. Later, the peripheral device manufacturer must support each driver released and provide updates to the drivers as problems are fixed.
In many ways, the success of a peripheral device can depend a great deal on the quality of the device drivers. A serious mistake or flaw in a device driver developed for a new operating environment or application can often cause the peripheral device to fail or produce less than optimal results. This results in wide spread customer dissatisfaction with a peripheral device even though the device is capable of producing higher quality results or output. For example, a printer capable of high resolution printing such as 1200 dpi may work suboptimal with an old or defective driver by falling back to a lower resolution such as 300 dpi. A user may return the printer because of the apparent defect or low quality even though the problem is with the driver and not the printer.
Setting up and administering peripheral devices is also difficult in a heterogeneous environment since so many devices have different capabilities and diagnostic conditions. In many cases, each different peripheral device comes with stand-alone diagnostic application and drivers which must be installed on each machine that interacts with the device. These various diagnostic tools are typically proprietary and communicate with each peripheral device based on proprietary predetermined hardware signals. The interpretation of these signals is left up to logic contained within each diagnostic software application and varies from device to device. For example, a hardware signal generated from one printer device may indicate that the printer is "out of paper" while the same signal transmitted to a second printer device may cause the printer and host computer to crash or "lock-up". Accordingly, the proprietary nature of current peripheral device architecture designs makes it infeasible to use a single application to manage a large heterogeneous collection of peripheral devices.
Several companies have attempted to solve incompatibilities between peripheral devices by creating several different page description layout (PDL) languages. Unfortunately, PDL languages do not properly address all the shortfalls associated with controlling peripheral devices. Even though, these page description languages organize the layout of page information in a programmatic manner they do not allow general purpose processing. For example, PostScript, PCL, Adobe Acrobat, Adobe PrintGear, Microsoft Graphics Device Interface, and Apple QuickDraw are all different PDL language variations which describe how data should be placed on the page but do not enable the printer to perform general purpose operations. Further, existing PDL languages are generally too complex and limited to develop important applications such as conversion routines to convert between different image formats such as between TIFF, GIF, and JPEG. Essentially, these PDL languages only simplify the portion of printing which deals with page layout on a printer but do not simplify all the problems associated with peripheral device compatibility.
PDL languages are also unsuccessful in increasing peripheral device compatibility because no particular PDL language has been widely accepted. This has caused the peripheral market to become fragmented among different standards such as PCL (printer control language) and PostScript. Ironically, this has caused device driver development to become even more complex as the peripheral device manufacturers and users must deal with more, not less, device drivers and options. Under the current technology, this means that users can be required to load more device drivers in order to match the personality of the printer (e.g. PostScript, PCL) and the application being used. Accordingly, the various PDL languages being used have actually made peripheral device control and management more complex.
What is needed is a peripheral device architecture which integrates software applications with the peripheral device hardware in a uniform manner. Applications written to work with one brand and make of peripheral device should also be able to function with another brand and make of a peripheral device without loading new drivers, new software, or new versions. Users should be able to use a wide range of peripheral devices and distribute processing over an intranet or the Internet to the peripheral devices most appropriate for the application. Further, status and diagnostics should be readily available on a single application from a wide range of peripheral devices.